K your research substances, start with Chemical A thorough literature search is impossible without a system of surveying the field and selecting for closer study the papers truly relevant to your interest. For thousands of researchers around the world, this selection process begins with Chemical Abstracts Service (CAS) Indexes.
The Secret of Systematic Indexing... One Substance Gets One Name Chemical substances present a special searching problem because one substance may go by many names. The drug Chlorpromazine is a good example. Different journal articles call it "Aminazin," "Clorpromazin," "Propaphenin," or "2-Chloro-10(3-dimethylaminopropyl) phenothiazine." There are at least 100 designations (including trade names) for this one substance: CH2CH2CH2N(CH3)2
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Do you need to look up 100 names for Chlorpromazine to avoid missing literature on
this drug? Not if you use the CAS Indexes to CHEMICAL ABSTRACTS (CA). In CA, one substance goes by one name—the CA Index Name. That's why all references to a given substance are found at one place in the CA Chemical Substance Index. Find the name and you'll find the references—it's simpler than you might think. CA Index Names exemplify the controlled vocabulary used in CA indexes to assure that all substances will be referenced consistently. These names are chosen according to accepted recommendations of the International Union of Pure and Applied Chemistry (IUPAC). By indexing the same substances always in the same way, CA avoids the confusion caused by differences in terminology used in the original literature. Moreover, most CA Index Names are precisely descriptive of a substance's molecular structure. This is an important benefit, because you can translate the name into the structure from which it was derived, and vice versa. CA chemical substance names became more systematic with the beginning of the CA Ninth Collective Index period (1972-1976). Many nonsystematic names were cross-referred to more fully systematic names in order to
improve searching of a single substance and its closely akin derivatives. Fully systematic names permit structurally related substances to be grouped alphabetically in the CA Chemical Substance Index. This is another contribution to efficient searching, and it was impossible when many nonsystematic, common language terms were used. To search chemical substance references in earlier CA volumes, you should use the CA Formula Index. This will connect you with the relevant literature even though a substance's CA Index Name may have changed from one Collective Period to another. You should also check the CA Index Guide covering the period of your search to find the Index Name used at that time for a given substance.
Three Steps Toward Efficient Literature Searching A study of Chlorpromazine involves checking three CAS publications. You can find references on many chemical substances by following essentially the same steps:
concerns chemical it should Abstracts Indexes. 1. Find the CA Index Name First, looking up Chlorpromazine in the CA INDEX GUIDE, you find the following entry: Chlorpromazine See WH-Phenothiazine-10-propanamine, 2-chloro-N,N-dimethyl(50-53-3)
This is the fully systematic CA Index Name. It designates the unique molecular structure and eliminates the ambiguity arising from trade names and "common language" terms applied to this drug. The five-digit number in brackets is the CAS Registry Number; it has no structural significance but provides a concise identification (somewhat like asocial security number) for the substance. 2. Go to the CA Indexes
lOtf-Phenothiazine-lO-propanamine
— , 2-chloro-N^V-dimethyl- (chlorpromazine) [50-53-3J 10tf-Phenothiazine-10-propanamine, 2-chloro-NJV-dimethyl- [50 53 3], analysis detection of, by gas chromatog., 128228u detn. of in blood, 111152s in blood and urine, by gas chromatog., 128222n in blood and urine, in overdosage, 47872x
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Now that you have the CA Index Name, it's a simple matter to find literature references. Assuming that studies published after 1961 are of J< primary interest in this case, you go to the CA Seventh, Eighth, b and Ninth &*
Collective Indexes. Each covers five years (ten volumes) of CA: together, the three collectives provide access to all chemicallysignificant literature referenced in CA between 1962 and 1976. For more recent studies, check the semiannual CA Volume Indexes published since 1976. No matter what term was used for this drug in the literature, any study concerning Chlorpromazine is listed under the CA Index Name:
10/Y-Phenothiazine-10-propanamine, 2-chloro-N,yV-dimethyl- [50 53 3], biological studies absorption of, by cassava powder, in simulated stomach conditions, 178750d acetylcholine metab. by brain response to, 145828g acetylcholine of brain striatum response to, dibutyryl cyclic AMP in relation to, 127222a
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3. Read the Abstracts in CA Having obtained the pertinent abstract numbers, you then locate and read the abstracts in CA. These provide an excellent basis for deciding which documents you need to review in their entirety. Your literature study is well underway, and you can be sure you haven't missed any important sources of information.
The Result: More Information. Your Time More Effectively Utilized Searching scientific literature will never be easy. It takes considerable know-how on your part to discriminate between vitally important studies and those of marginal interest. But the job can be done more efficiently, reliably, and thoroughly with the help of abstracts and indexes from CAS. As long as chemistry-related information continues to grow, CA and its indexes will remain an excellent beginning for your research.
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Chemical Abstracts Service P.O. Box 3012 Columbus, Ohio 43210
